The model number internally says 509 but all of the documentation says 508.
I paid $2,000 used on ebay in 2003. I have had a couple of motor issues. The motor would only run at hi speed. This has happened twice to two different motors.(When I had the primary motor out for repair I swapped it out with the secondary motor) The centrifugal swith was burnt out and I managed to rebuild it myself. Someone else posted about the same issue on the same model tub. Typically this problem is caused by a bad motor control calling for high and low speeds at the same time.

Cost to fix ($14) since I did the work . If I had some one do the work it would have been at least $100 for labour and they would have swapped out the pump $300 +.

I have opted to replace the controller. $(275) + tax + shippng. If the pumps fail and I'm away and we have a freeze up then the tub would be junk..

Most of the jets have blown out due to the plastic disintegrating. I can't speak to the previous user but when I had the water ph was well maintained. Apparently poor pH balance can cause premature failure of the jet parts. I personally think they used lousy plastic for the application.
Until recently the plastic part that wears is not sold seperately you had to buy the entire jet assembly. 32 jets at $20 a jet + tax + shipping????
Lets call it an even $700 to replace them all.

$400 motor /pump
$400 motor /pump
$400 Controller
$100 labour to swap out controller.
$700 new jets

$2000 in repairs for a 5 year old tub..

My suggestion would be to avoid them unless your handy..